Method for preparing 1, 4-dioxane-2-ketone from ethylene carbonate

Abstract

The invention belongs to the field of chemistry and chemical engineering, and discloses a method for preparing 1, 4-dioxane-2-ketone from ethylene carbonate, the method takes bulk products glycollic acid derivatives and cyclic carbonate as raw materials, adopts a simple chemical as a catalyst, synthesizes 1, 4-dioxane-2-ketone through a one-step method, and can synthesize large-batch and high-yield 1, 4-dioxane-2-ketone at one time. Compared with the prior art, the method provided by the invention has the advantages that the reaction steps are greatly shortened, the energy consumption is greatly reduced, the synthesis yield of the 1, 4-dioxane-2-ketone is improved, the production cost is obviously reduced, and the method has a good application prospect.

Description

Technical Field

[0001] The invention relates to the field of chemistry and chemical engineering, and in particular to a method for preparing 1,4-dioxane-2-one from ethylene carbonate. Background Art

[0002] 1,4-dioxane-2-one (pDO for short) is an important organic chemical. It is a colorless crystal at room temperature. Its structure is a six-membered heterocyclic lactone containing ester bonds and ether bonds. It can be used as an antifungal agent or fragrance. More importantly, it is a monomer raw material for synthesizing biodegradable polyester materials poly (1,4-dioxane-2-one) (PpDO for short). However, the synthesis of large-scale, high-purity pDO monomers has always been a problem that has plagued its development. At present, pDO is still not a chemical that can be mass-produced, and the market price remains high. Therefore, developing new pDO synthesis methods and reducing the synthesis cost of pDO are the key to breaking the limitations of PpDO synthesis and achieving large-scale applications.

[0003] At present, there are two main methods for synthesizing 1,4-dioxane-2-one: one is to use diethylene glycol as the raw material, and to prepare pDO through catalytic oxidative dehydrogenation cyclization reaction. The other is to use ethylene glycol as the raw material, and to react with chloroacetic acid or chloroacetate to obtain hydroxy acid salt, and then to obtain it through esterification. Among them, the synthesis of pDO using ethylene glycol as the raw material and chloroacetic acid as the raw material is cumbersome and the reaction conditions are harsh. In addition, the process route of chloroacetic acid hydrolysis in the preparation process is seriously corrosive to the equipment and pollutes a lot, so it cannot be mass-produced. The preparation of pDO from diethylene glycol via catalytic oxidative dehydrogenation cyclization is a relatively mature method. However, since the catalytic dehydrogenation reaction is difficult to carry out, the method of synthesizing pDO from diethylene glycol is highly dependent on high-activity catalysts. Therefore, a lot of research has been conducted on the development of diethylene glycol dehydrogenation catalysts. The existing various catalysts have greatly improved the selectivity and yield of the synthesis of p-dioxanone. They are mainly based on metal compound catalysts, combined with alkali metals, alkaline earth metal compounds and rare earth metal compounds as co-catalysts, but the catalyst cost is still high, and it is difficult to ensure that the pDO product is free of metal residues. These challenges still restrict the synthesis of pDO.

[0004] Therefore, in view of the current difficulties of pDO such as high production cost and complex synthesis process, it is of great significance to develop a simpler, more environmentally friendly and safer pDO synthesis process and reduce or abandon the use of expensive catalysts or metal catalysts for the preparation of low-cost and high-purity pDO. Summary of the invention

[0005] The embodiment of the present invention provides a method for preparing 1,4-dioxane-2-one from ethylene carbonate, which can prepare 1,4-dioxane-2-one with high yield and high purity through a one-step synthesis method.

[0006] In a first aspect, the present invention provides a method for preparing 1,4-dioxane-2-one from ethylene carbonate, the method comprising:

[0007] A glycolic acid derivative, ethylene carbonate and a catalyst are mixed and reacted to obtain the 1,4-dioxane-2-one; wherein the glycolic acid derivative has the following structural formula:

[0008] In the formula, R is hydrogen, a C1-C8 alkyl group with a substituent, a C3-C8 cycloalkyl group with a substituent, an aromatic group with a substituent, or an aromatic heterocyclic group with a substituent; the substituent is a halogen, a C1-C3 alkyl group, a halogenated C1-C3 alkyl group, a C1-C3 alkoxy group, a hydroxyl group, a nitro group, or an amino group; and the heteroatom in the aromatic heterocyclic group is nitrogen, sulfur, or oxygen.

[0009] Preferably, the catalyst is selected from one or more of ammonium salt catalysts, quaternary ammonium salt catalysts, polyquaternary ammonium salt catalysts, quaternary phosphonium salt catalysts, inorganic acid catalysts, organic acid catalysts, inorganic base catalysts, organic base catalysts, Lewis acid-base pair catalysts, ionic liquid catalysts, solid alkaline catalysts, solid acid catalysts, and metal salt catalysts.

[0010] Preferably, the structural formula of the quaternary ammonium salt catalyst is as follows:

[0011] R is a C1-C 22 Alkyl, aromatic group with a substituent or aromatic heterocyclic group with a substituent; the substituent is C1-C 10 Alkyl, C1-C 10 Alkoxy or hydroxy, the heteroatom in the aromatic heterocyclic group is nitrogen, sulfur or oxygen; X is fluoride, chloride, bromide, iodide, carboxylate, sulfate, sulfite, bisulfate, nitrate, nitrite, carbonate, bicarbonate, chlorate, phosphate, borate, silicate or sulfonate.

[0012] Preferably, the ammonium salt catalyst is selected from one or more of ammonium fluoride, ammonium chloride, ammonium bromide and ammonium iodide;

[0013] The quaternary phosphonium salt is selected from one or more of methyltriphenylphosphonium chloride, benzyltriphenylphosphonium chloride, tetraphenylphosphonium chloride, trihexyltetradecylphosphonium chloride, tetrabutylphosphonium chloride, methoxymethyltriphenylphosphonium chloride, methyltriphenylphosphonium bromide, benzyltriphenylphosphonium bromide, tetraphenylphosphonium bromide, trihexyltetradecylphosphonium bromide, tetrabutylphosphonium bromide and methoxymethyltriphenylphosphonium bromide;

[0014] The polyquaternium salt is selected from one or more of polyquaternium-6, polyquaternium-10, and polyquaternium-55;

[0015] The inorganic acid catalyst is selected from one or more of sulfuric acid, hydrochloric acid, hydrobromic acid, tungstic acid, titanic acid, and boric acid;

[0016] The organic acid catalyst is selected from one or more of methanesulfonic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid, boron trifluoride, boron trifluoride ethyl ether, tri(pentafluorophenyl)boron, triethylboron, camphorsulfonic acid, benzoic acid, salicylic acid, oxalic acid, and malic acid;

[0017] The inorganic base catalyst is selected from one or more of sodium hydride, lithium hydride, calcium hydride, sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, lithium hydroxide, magnesium hydroxide, zinc hydroxide, copper hydroxide, iron hydroxide, and ammonium hydroxide;

[0018] The organic base catalyst is selected from one or more of triethylamine, pyridine, 4-dimethylaminopyridine, 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, and hexamethyldisilazane;

[0019] The metal salt catalyst is selected from one or more of copper tetrafluoroborate, bismuth trifluoride, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, calcium carbonate, cesium carbonate, sodium glycolate, sodium acetate, lithium diisopropylamide, sodium methoxide, sodium ethoxide, sodium tert-butoxide, potassium tert-butoxide, n-butyl lithium, and isobutyl lithium;

[0020] The ionic liquid catalyst is selected from one or more of imidazole ionic liquids, pyridine ionic liquids, quaternary ammonium salt ionic liquids, and quaternary phosphonium salt ionic liquids;

[0021] The solid acid catalyst is selected from one or more of supported acid catalysts, acidic molecular sieves, cation exchange resins, natural clays, metal sulfur or oxides, and acidic catalyst complexes;

[0022] The solid base catalyst is selected from one or more of supported base catalysts, acidic molecular sieves, anion exchange resins, alkali metal sulfur or oxides, and alkaline catalyst complexes.

[0023] Preferably, the molar ratio of the catalyst to the ethylene carbonate is 1:50 to 1:1000.

[0024] Preferably, the molar ratio of the glycolic acid derivative to the ethylene carbonate is 10:1 to 1:10.

[0025] Preferably, before stirring and mixing, the method further includes adding an organic solvent to the reaction system: wherein the organic solvent is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, tetrahydrofuran, dioxane, dichloroethane, chloroform, carbon tetrachloride, toluene, xylene, and trimethylbenzene.

[0026] Preferably, the reaction temperature is 0 to 200° C., and the reaction time is 1 to 24 hours.

[0027] Preferably, after the reaction is completed, the method further comprises the steps of separating and purifying the obtained crude product in sequence.

[0028] In a second aspect, the present invention provides 1,4-dioxane-2-one, which is prepared by any of the methods described in the first aspect above.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects:

[0030] (1) In the present invention, two bulk chemicals, glycolic acid derivatives and ethylene carbonate, are used as reaction raw materials, and suitable catalyst types are selected to promote the complete conversion of the two raw materials. The reaction raw materials and the catalyst are mixed and stirred to prepare 1,4-dioxane-2-one through a one-step reaction. This method significantly shortens the reaction time and reaction steps of the synthesis, and can significantly improve the yield, which can reach a maximum of more than 90%;

[0031] (2) The synthesis process of the present invention is simple. The reaction can be started by mixing and stirring the raw materials and the catalyst. The reaction is carried out under air conditions and is not sensitive to pressure conditions. Therefore, the reaction device that can be selected is simple, has a wide range of applicable scenarios, and increases the safety factor of the reaction. In addition, the catalysts selected in the reaction process are all bulk chemicals with low cost of use, and most of them are non-metallic catalysts, and the products have no metal residues. In addition, the catalysts are mostly salts with stable structures, low toxicity, low volatility, and low corrosiveness, and have little effect on the synthesis device and environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 is a nuclear magnetic resonance spectrum of high-purity 1,4-dioxane-2-one provided in Example 2 of the present invention;

[0034] Figure 2 is a gas chromatogram of high-purity 1,4-dioxane-2-one provided in Example 2 of the present invention;

[0035] Figure 3 This is a mass spectrum of high-purity 1,4-dioxane-2-one provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0037] Ethylene carbonate is a five-membered cyclic carbonate. Due to its stable chemical properties, it is often used as a green and environmentally friendly organic solvent. It can also be used as an organic compound in printing and dyeing, plastics, gas separation, polymer synthesis and electrochemistry. However, there is an overcapacity of ethylene carbonate at this stage, so it is imperative to develop its high-value conversion. If a method can be developed to synthesize 1,4-dioxane-2-one (pDO) using bulk chemicals as raw materials, it can not only reduce the production cost of pDO, but also realize the high-value utilization of low-value chemicals.

[0038] Therefore, in view of the current problems of high cost of pDO caused by complicated production process, harsh reaction conditions, low yield and expensive catalyst, as well as a series of problems such as low product purity caused by metal residues and many side reactions, the present invention considers using bulk glycolate and ethylene carbonate bulk chemicals as raw materials and cheap and easily available organic salts and other compounds as efficient catalysts to prepare pDO through a simple and fast synthesis process. This can not only reduce the production cost of pDO, but also achieve high-value utilization of low-value chemicals.

[0039] like Figure 1As shown, the present invention provides a method for preparing 1,4-dioxane-2-one from ethylene carbonate, the method comprising:

[0040] A glycolic acid derivative, ethylene carbonate and a catalyst are mixed and reacted to obtain the 1,4-dioxane-2-one; wherein the glycolic acid derivative has the following structural formula:

[0041] In the formula, R is hydrogen, a C1-C8 alkyl group with a substituent, a C3-C8 cycloalkyl group with a substituent, an aromatic group with a substituent, or an aromatic heterocyclic group with a substituent; the substituent is a halogen, a C1-C3 alkyl group, a halogenated C1-C3 alkyl group, a C1-C3 alkoxy group, a hydroxyl group, a nitro group, or an amino group; and the heteroatom in the aromatic heterocyclic group is nitrogen, sulfur, or oxygen.

[0042] In the embodiment of the present invention, two bulk chemicals, glycolic acid derivatives and ethylene carbonate, are used as reaction raw materials, and suitable catalyst types are selected to promote the complete conversion of the two raw materials. The reaction raw materials and the catalyst are mixed and stirred to prepare 1,4-dioxane-2-one through a one-step reaction, wherein the synthesis route of 1,4-dioxane-2-one is as follows:

[0043]

[0044] As can be seen from the above reaction formula, using bulk chemicals glycolic acid derivatives and ethylene carbonate as reaction raw materials, since glycolic acid derivatives have double bonds that can participate in the reaction, they can undergo a ring-opening reaction with ethylene carbonate under the catalytic action of a catalyst, thereby forming 1,4-dioxane-2-one in a one-step process; this method significantly shortens the reaction time and reaction steps of the synthesis, and can significantly improve the yield, which can reach more than 90%. In addition, the reaction raw materials used are all low-cost bulk chemicals, which reduces product costs, has high product added value, and has a wide range of raw material sources, avoiding the problem of being restricted by raw material sources, and provides a practical method for the industrial production of 1,4-dioxane-2-one.

[0045] According to some preferred embodiments, the glycolic acid derivative is glycolic acid, methyl glycolate, ethyl glycolate, n-propyl glycolate, isopropyl glycolate, n-butyl glycolate, isobutyl glycolate, tert-butyl glycolate, phenyl glycolate or benzyl glycolate.

[0046] In the embodiment of the present invention, when the glycolic acid derivative is of the above type, it is more conducive to quickly synthesizing a large amount of 1,4-dioxane-2-one through reaction with ethylene carbonate.

[0047] According to some preferred embodiments, the catalyst is selected from one or more of ammonium salt catalysts, quaternary ammonium salt catalysts, polyquaternary ammonium salt catalysts, quaternary phosphonium salt catalysts, inorganic acid catalysts, organic acid catalysts, inorganic base catalysts, organic base catalysts, Lewis acid-base pair catalysts, ionic liquid catalysts, solid alkaline catalysts, solid acid catalysts, and metal salt catalysts.

[0048] In the synthesis method of the present invention, an efficient catalyst is one of the keys to catalyze the reaction between glycolic acid derivatives and ethylene carbonate. In the embodiments of the present invention, the above-mentioned type of catalyst is obtained through a large number of screenings. On the one hand, the price of this type of catalyst is low, which can effectively reduce the production cost. On the other hand, this type of catalyst has a high selectivity for the ring-opening position of ethylene carbonate, and has a high catalytic activity for the hydroxyl group in the glycolic acid derivative to attack ethylene carbonate, which can significantly accelerate the reaction rate of the glycolic acid derivative and ethylene carbonate and improve the reaction yield.

[0049] According to some preferred embodiments, the structural formula of the quaternary ammonium salt catalyst is as follows:

[0050] R is a C1-C 22 Alkyl, aromatic group with a substituent or aromatic heterocyclic group with a substituent; the substituent is C1-C 10 Alkyl, C1-C 10 Alkoxy or hydroxy, the heteroatom in the aromatic heterocyclic group is nitrogen, sulfur or oxygen; X is fluoride, chloride, bromide, iodide, carboxylate, sulfate, sulfite, bisulfate, nitrate, nitrite, carbonate, bicarbonate, chlorate, phosphate, borate, silicate or sulfonate.

[0051] According to some preferred embodiments, the quaternary ammonium salt catalyst is tetramethylammonium fluoride, tetramethylammonium fluoride tetrahydrate, tetramethylammonium chloride, tetramethylammonium acetate, tetramethylammonium borohydride, tetramethylammonium p-toluenesulfonate, tetramethylammonium hydroxide, tetrapropylammonium hydroxide, tetramethylammonium bromide, tetramethylammonium iodide, tetraethylammonium fluoride, tetraethylammonium fluoride dihydrate, tetraethylammonium chloride, tetraethylammonium bromide, tetraethylammonium iodide, tetrapropylammonium fluoride, tetrapropylammonium chloride, tetrapropylammonium bromide, tetrapropylammonium iodide, tetrabutylammonium fluoride, tetrabutylammonium fluoride trihydrate, tetrabutylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium iodide, tetrapentylammonium fluoride, tetrapentylammonium chloride, tetrapentylammonium bromide, tetrapentylammonium iodide, tetrahexylammonium fluoride, tetrahexylammonium chloride , tetrahexylammonium bromide, tetrahexylammonium iodide, tetraheptylammonium fluoride, tetraheptylammonium chloride, tetraheptylammonium bromide, tetraheptylammonium iodide, tetraoctylammonium fluoride, tetraoctylammonium chloride, tetraoctylammonium bromide, tetraoctylammonium iodide, tetranonylammonium fluoride, tetranonylammonium chloride, tetranonylammonium bromide, tetranonylammonium iodide, tetradecylammonium fluoride, tetradecylammonium chloride, tetradecylammonium bromide, tetradecylammonium iodide, dodecyltrimethylammonium fluoride, dodecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, dodecyltrimethylammonium iodide, undecyltrimethylammonium fluoride, undecyltrimethylammonium chloride, undecyltrimethylammonium bromide, undecyltrimethylammonium iodide, dodecyltrimethylammonium fluoride, dodecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, dodecyltrimethylammonium Alkyltrimethylammonium iodide, tridecyltrimethylammonium fluoride, tridecyltrimethylammonium chloride, tridecyltrimethylammonium bromide, tridecyltrimethylammonium iodide, tetradecyltrimethylammonium fluoride, tetradecyltrimethylammonium chloride, tetradecyltrimethylammonium bromide, tetradecyltrimethylammonium iodide, pentadecyltrimethylammonium fluoride, pentadecyltrimethylammonium chloride, pentadecyltrimethylammonium bromide, pentadecyltrimethylammonium iodide, hexadecyltrimethylammonium fluoride, hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium iodide, octadecyltrimethylammonium fluoride, octadecyltrimethylammonium chloride, octadecyltrimethylammonium bromide, octadecyltrimethylammonium iodide, eicosyltrimethylammonium fluoride, eicosyltrimethyl one or more of alkylammonium chloride, arachidyltrimethylammonium bromide, arachidyltrimethylammonium iodide, behenyltrimethylammonium fluoride, behenyltrimethylammonium chloride, behenyltrimethylammonium bromide, behenyltrimethylammonium iodide, phenyltrimethylammonium fluoride, phenyltrimethylammonium chloride, phenyltrimethylammonium bromide, phenyltrimethylammonium iodide, benzyltrimethylammonium fluoride, benzyltrimethylammonium chloride, benzyltrimethylammonium bromide, benzyltrimethylammonium iodide, single-chain quaternary ammonium salt (dodecyldimethylbenzylammonium chloride), double-chain quaternary ammonium salt (diethyldimethylammonium chloride), double-chain quaternary ammonium salt (didecyldimethylammonium chloride), bis(triphenylphosphorane)ammonium chloride, pyridine halide, imidazole bromide, and 1-butyl-1-methylpyrrolidino bromide;

[0052] According to some preferred embodiments, the ammonium salt catalyst is selected from one or more of ammonium fluoride, ammonium chloride, ammonium bromide, and ammonium iodide;

[0053] The quaternary phosphonium salt is selected from one or more of methyltriphenylphosphonium chloride, benzyltriphenylphosphonium chloride, tetraphenylphosphonium chloride, trihexyltetradecylphosphonium chloride, tetrabutylphosphonium chloride, methoxymethyltriphenylphosphonium chloride, methyltriphenylphosphonium bromide, benzyltriphenylphosphonium bromide, tetraphenylphosphonium bromide, trihexyltetradecylphosphonium bromide, tetrabutylphosphonium bromide and methoxymethyltriphenylphosphonium bromide;

[0054] The polyquaternium salt is selected from one or more of dimethyldiallyl ammonium chloride homopolymer (polyquaternium-6), chlorinated-2-hydroxy-3-(trimethylamino)propyl polyethylene oxide cellulose ether (polyquaternium-10), and polyquaternium-55;

[0055] The inorganic acid catalyst is selected from one or more of sulfuric acid, hydrochloric acid, hydrobromic acid, tungstic acid, titanic acid, and boric acid;

[0056] The organic acid catalyst is selected from one or more of methanesulfonic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid, boron trifluoride, boron trifluoride ethyl ether, tri(pentafluorophenyl)boron, triethylboron, camphorsulfonic acid, benzoic acid, salicylic acid, oxalic acid, and malic acid;

[0057] The inorganic base catalyst is selected from one or more of sodium hydride, lithium hydride, calcium hydride, sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, lithium hydroxide, magnesium hydroxide, zinc hydroxide, copper hydroxide, iron hydroxide, and ammonium hydroxide;

[0058] The organic base catalyst is selected from one or more of triethylamine, pyridine, 4-dimethylaminopyridine, 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, and hexamethyldisilazane;

[0059] The metal salt catalyst is selected from one or more of copper tetrafluoroborate, bismuth trifluoride, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, calcium carbonate, cesium carbonate, sodium glycolate, sodium acetate, lithium diisopropylamide, sodium methoxide, sodium ethoxide, sodium tert-butoxide, potassium tert-butoxide, n-butyl lithium, and isobutyl lithium;

[0060] The ionic liquid catalyst is selected from one or more of imidazole ionic liquids, pyridine ionic liquids, quaternary ammonium salt ionic liquids, and quaternary phosphonium salt ionic liquids;

[0061] The solid acid catalyst is selected from one or more of supported acid catalysts, acidic molecular sieves, cation exchange resins, natural clays, metal sulfur or oxides, and acidic catalyst complexes;

[0062] The solid base catalyst is selected from one or more of supported base catalysts, acidic molecular sieves, anion exchange resins, alkali metal sulfur or oxides, and alkaline catalyst complexes.

[0063] In the embodiment of the present invention, when a quaternary ammonium salt catalyst is used to catalyze the reaction of glycolic acid derivatives and ethylene carbonate, the yield of the prepared pDO can be guaranteed to be as high as 80-99%, and the molar ratio of the quaternary ammonium salt catalyst to the raw material ethylene carbonate is controlled to be 1:50-1:1000 to complete the reaction, thereby reducing the catalyst residue and the difficulty of purification; at the same time, considering that the quaternary ammonium salt catalyst is stable in nature, low in toxicity, easy to store and extremely low in cost, the quaternary ammonium salt catalyst is a preferred catalyst type in the pDO synthesis reaction method of the present invention.

[0064] The experiment of the present invention confirms that the organic base catalyst and the inorganic base catalyst can also catalyze the synthesis of pDO reaction of the present invention. The reaction yield of such catalyst is moderate, the pDO yield is 60-90%, and the reaction temperature is lower than that of the quaternary ammonium salt catalyst, but the dosage is slightly higher than that of the quaternary ammonium salt catalyst. The dosage range of the organic base catalyst and the inorganic base catalyst in the embodiment of the present invention is 1:50-1:100, and the dosage range of the quaternary ammonium salt catalyst is 1:100-1:1000. Acidic catalysts can also catalyze the synthesis of pDO, but the yield is relatively low. In addition, Lewis acid-base catalysts and ionic liquid catalysts can also play a good catalytic role in the reaction.

[0065] In the embodiment of the present invention, when the catalyst is a solid acid catalyst or a solid base catalyst, the solid acid catalyst or the solid base catalyst can be loaded into a plurality of stainless steel reaction tubes connected in series, and the solid catalyst is compacted in the reaction tube using an apparatus and high-pressure air ventilation pressure, and the inlet section is connected to a peristaltic pump after the catalyst is loaded, and then a receiving bottle is placed at the outlet section, and finally the reaction tube is placed in a column oven; when reacting, the glycolic acid derivative and ethylene carbonate are mixed and put into the reaction tube, and are pressed into the reactor at a flow rate of 0.1 to 1 mL / min, and the temperature of the column oven is set to 150 to 250° C. After stabilization, the pump switch is turned on, and the reaction begins when the mixed raw materials enter the reaction tube, and at the same time, the reaction pressure is observed to see whether it exceeds the upper limit of the pressure, and the product is adjusted at the outlet to receive a certain amount of the product, and the unreacted glycolic acid derivative and ethylene carbonate are recovered by reduced pressure distillation at 30 to 70° C., and then re-added to the raw material tank, and pDO is collected by reduced pressure distillation at 90 to 100° C., and pDO is purified by two distillations to finally obtain high-purity pDO. This continuous synthesis process is more suitable for industrial production under certain conditions.

[0066] It should be noted that when the catalyst is a series of solid catalysts such as ion exchange resins, molecular sieves, and supported catalysts, a solid-liquid heterogeneous reaction can be carried out in the reaction device. After the reaction is completed, the solid catalyst can be recovered by filtration or centrifugation, and can be used again for catalytic synthesis after washing and activation.

[0067] According to some preferred embodiments, the molar ratio of the catalyst to the ethylene carbonate is 1:50 to 1:1000 (for example, 1:20, 1:50, 1:100, 1:500, 1:1000, 1:5000 or 1:10000).

[0068] According to some preferred embodiments, the molar ratio of the glycolic acid derivative to the ethylene carbonate is 10:1 to 1:10 (for example, 10:1, 8:1, 5:1, 3:1, 2:1, 1:1, 1:2, 1:3, 1:5, 1:8 or 1:10).

[0069] In the embodiment of the present invention, the molar ratio of the catalyst to ethylene carbonate can be selected within the above range according to the type of different catalysts. A high-activity catalyst is used in a small amount, such as quaternary ammonium salts and quaternary phosphonium salts, and a low-activity catalyst is used in a large amount, such as organic bases or inorganic bases. The molar ratio of glycolic acid derivatives and ethylene carbonate can fluctuate between 10:1 and 1:10, which can promote the reaction to a certain extent, and the excess raw materials can be recovered by distillation and the like. Preferably, the molar ratio of glycolic acid derivatives and ethylene carbonate can fluctuate between 2:1 and 1:2; further, when the molar ratio of glycolic acid derivatives to ethylene carbonate is selected at 1:1, glycolic acid derivatives and ethylene carbonate can be completely converted, and the two raw materials can be 100% utilized, so that the product does not contain raw materials, reduces the difficulty of purification, and improves the purity of the product.

[0070] According to some preferred embodiments, before stirring and mixing, the step of adding an organic solvent to the reaction system is also included: wherein the organic solvent is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, tetrahydrofuran, dioxane, dichloroethane, chloroform, carbon tetrachloride, toluene, xylene, and trimethylbenzene.

[0071] In the embodiment of the present invention, under the reaction conditions, the glycolic acid derivative and the ethylene carbonate are both liquids, and the two raw materials are highly miscible and have good solubility in the catalyst. Therefore, the synthesis process in the embodiment of the present invention can be carried out under solvent-free bulk conditions, thereby simplifying the purification steps, ensuring the purity of the product, and reducing the generation of waste liquid.

[0072] Under specific conditions and devices, the synthesis process in the embodiment of the present invention can also be carried out under bulk conditions containing organic solvents. At this time, it is necessary to select some reagents that do not contain active groups as solvents to reduce the viscosity of the system. For example, various aliphatic and aromatic hydrocarbons, ethers or amides can be selected, such as tetrahydrofuran, ether, dioxane, toluene, xylene, trimethylbenzene, dichloromethane, dichloroethane, carbon tetrachloride, N,N-dimethylformamide, N-methylpyrrolidone, etc.

[0073] According to some preferred embodiments, the reaction temperature is 0-200°C (for example, it can be 0°C, 10°C, 50°C, 80°C, 100°C, 150°C or 200°C), and the reaction time is 1-24h (for example, it can be 1h, 5h, 8h, 12h, 16h, 18h or 24h).

[0074] In the synthesis method of the present invention, the reaction temperature of the glycolic acid derivative and ethylene carbonate can be selected between 0 and 200° C. according to different types of catalysts. It has been confirmed by experiments of the present invention that when the reaction is carried out under heating conditions (60-200° C.), the catalyst can be used to catalyze the ring-opening reaction of ethylene carbonate with a stable five-membered ring structure, and the reaction temperature is increased within a certain range, which is beneficial to shortening the reaction time without affecting the purity and yield of the product.

[0075] At the same time, the synthesis process in the embodiment of the present invention can be carried out under air conditions, avoiding the use of inert gas; the synthesis process can also be carried out in a closed environment, in an inert atmosphere, under pressurized, vacuum and other conditions. Carrying out the synthesis process under air atmosphere does not affect the final synthesis yield, thereby ensuring the safety of the synthesis process and being applicable to different reaction devices and conditions.

[0076] According to some preferred embodiments, after the reaction is completed, the steps of separating and purifying the crude product obtained by the reaction are further included.

[0077] In the embodiments of the present invention, for general catalysts such as quaternary ammonium salts and quaternary phosphonium salts, after the reaction is completed, distillation can be directly performed for purification to obtain high-purity pDO; for acidic and basic catalysts, weak acids and weak bases need to be added for neutralization and quenching after the reaction is completed to avoid side reactions during the purification process; for solid catalysts or supported catalysts, filtration is performed before purification to separate the catalyst for reuse, and no chemical reaction occurs during the purification process; pDO can be subjected to multiple reduced pressure distillations to ensure high purity and reduce water content, and can also be subjected to dissolution-crystallization recrystallization purification using solvents such as dichloromethane, tetrahydrofuran, and ethyl acetate to obtain high-purity pDO crystals.

[0078] The present invention also provides high-purity 1,4-dioxane-2-one, which is prepared by the low-cost preparation method provided by the present invention.

[0079] In summary, in the embodiment of the present invention, bulk products of glycolic acid derivatives and ethylene carbonate are used as reaction raw materials to synthesize 1,4-dioxane-2-one by a one-step method under catalyst-promoted conditions. By rationally controlling the types and proportions of each raw material during the reaction, the by-products in the reaction process are less, the final yield can be as high as 99%, the purity exceeds 99.5%, and the energy consumption and production cost are greatly reduced. The catalyst used in the synthesis method in the embodiment of the present invention is a cheap and readily available commercial chemical. A small amount of catalyst can achieve a high conversion rate and effectively inhibit the side reactions during the reaction. At the same time, the present invention only uses distillation, crystallization or sublimation to purify the product, ensuring the high purity and high yield of the pDO product.

[0080] In summary, the method for preparing 1,4-dioxane-2-one from ethylene carbonate in the embodiment of the present invention has good application prospects and value.

[0081] In order to more clearly illustrate the technical solution and advantages of the present invention, a method for preparing 1,4-dioxane-2-one from ethylene carbonate is described in detail below through several embodiments.

[0082] A. Synthesis of 1,4-dioxane-2-one (pDO) catalyzed by ammonium salt catalysts with glycolic acid derivatives and ethylene carbonate

[0083] Embodiment 1:

[0084] Under air atmosphere, add 76g glycolic acid (1.0mol), 88g ethylene carbonate (1.0mol) and 2.78g tetrabutylammonium chloride (0.01mol) into the reaction bottle, stir at 180°C for 12 hours, return to room temperature after the reaction, wash with sodium bicarbonate aqueous solution to remove glycolic acid, and finally collect pDO by reduced pressure distillation at 90-100°C, with a yield of 85%.

[0085] Embodiment 2:

[0086] Under air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 2.78 g of tetrabutylammonium chloride (0.01 mol) were added into the reaction bottle and stirred at 180°C for 12 hours. After the reaction was completed, the temperature was restored to room temperature and pDO was collected by reduced pressure distillation at 90-100°C with a yield of 99%.

[0087] pass Figure 1 The H-NMR spectrum test attributed all chemical shift signals, and the integrated area ratio of the three groups of peaks was 2:2:2, corresponding to the three methylene structures respectively; Figure 2Only one signal peak appeared in the gas chromatography test, proving that the purity of pDO was 100%; Figure 3 The molecular weight of 103.1 in the mass spectrum corresponds to the molecular weight of the pDO hydrogen ion, further demonstrating the chemical structure of pDO and the success of the method of the present invention.

[0088] Embodiment 3:

[0089] Under air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 0.28 g of tetrabutylammonium chloride (0.001 mol) were added into the reaction bottle and stirred at 180°C for 24 hours. After the reaction was completed, the temperature was restored to room temperature and pDO was collected by reduced pressure distillation at 90-100°C with a yield of 88%.

[0090] Embodiment 4:

[0091] Under air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 2.78 g of tetrabutylammonium chloride (0.01 mol) were added into the reaction bottle and stirred at 140°C for 24 hours. After the reaction was completed, the temperature was restored to room temperature and pDO was collected by reduced pressure distillation at 90-100°C with a yield of 70%.

[0092] Embodiment 5:

[0093] Under air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 2.78 g of tetrabutylammonium chloride (0.01 mol) were added into the reaction bottle and stirred at 160°C for 24 hours. After the reaction was completed, the temperature was restored to room temperature and pDO was collected by reduced pressure distillation at 90-100°C with a yield of 90%.

[0094] Embodiment 6:

[0095] In an air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 1.10 g of tetramethylammonium chloride (0.004 mol) were added into a reaction bottle and stirred at 180°C for 12 hours. After the reaction was completed, the temperature was restored to room temperature and pDO was collected by reduced pressure distillation at 90-100°C with a yield of 91%.

[0096] Embodiment 7:

[0097] In an air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 0.93 g of tetrabutylammonium fluoride (0.004 mol) were added to a reaction bottle and stirred at 180°C for 12 hours. After the reaction was completed, the temperature was restored to room temperature and pDO was collected by reduced pressure distillation at 90-100°C with a yield of 95%.

[0098] Embodiment 8:

[0099] In an air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 3.22 g of tetrabutylammonium bromide (0.012 mol) were added into a reaction bottle and stirred at 180°C for 12 hours. After the reaction was completed, the temperature was restored to room temperature and pDO was collected by reduced pressure distillation at 90-100°C with a yield of 95%.

[0100] Embodiment 9:

[0101] Under air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 0.53 g of ammonium chloride (0.01 mol) were added into a reaction bottle and stirred at 180°C for 12 hours. After the reaction was completed, the temperature was restored to room temperature and pDO was collected by reduced pressure distillation at 90-100°C with a yield of 75%.

[0102] Embodiment 10:

[0103] In an air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 2.36 g of dodecyltrimethylammonium chloride (0.01 mol) were added into a reaction bottle and stirred at 180°C for 12 hours. After the reaction was completed, the temperature was restored to room temperature and pDO was collected by reduced pressure distillation at 90-100°C with a yield of 91%.

[0104] Embodiment 11:

[0105] In an air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 3.48 g of octadecyltrimethylammonium chloride (0.01 mol) were added to a reaction bottle and stirred at 180°C for 12 hours. After the reaction was completed, the temperature was restored to room temperature and pDO was collected by reduced pressure distillation at 90-100°C with a yield of 93%.

[0106] Embodiment 12:

[0107] Under air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 1.72 g of phenyltrimethylammonium chloride (0.01 mol) were added into a reaction bottle and stirred at 180°C for 12 hours. After the reaction was completed, the temperature was restored to room temperature and pDO was collected by reduced pressure distillation at 90-100°C with a yield of 90%.

[0108] Embodiment 13:

[0109] In an air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 3.62 g of didecyldimethylammonium chloride (0.01 mol) were added into a reaction bottle and stirred at 180°C for 12 hours. After the reaction was completed, the temperature was restored to room temperature and pDO was collected by reduced pressure distillation at 90-100°C with a yield of 96%.

[0110] Embodiment 14:

[0111] In an air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 5.74 g of bis(triphenylphosphoryl)ammonium chloride (0.01 mol) were added into a reaction bottle and stirred at 180°C for 12 hours. After the reaction was completed, the temperature was restored to room temperature and pDO was collected by reduced pressure distillation at 90-100°C with a yield of 92%.

[0112] Embodiment 15:

[0113] Under air atmosphere, 1000 g of methyl glycolate (11.1 mol), 978 g of ethylene carbonate (11.1 mol) and 30.9 g of tetrabutylammonium chloride (0.11 mol) were added into a reaction bottle and stirred at 180°C for 16 hours. After the reaction was completed, the temperature was restored to room temperature and pDO was collected by reduced pressure distillation at 90-100°C with a yield of 97%.

[0114] Embodiment 16:

[0115] In an air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 2.78 g of tetrabutylammonium chloride (0.01 mol) were added to the reaction bottle, and then 100 mL of N,N-dimethylformamide was added, and stirred at 180°C for 12 hours. After the reaction was completed, the temperature was restored to room temperature. N,N-dimethylformamide was first removed by vacuum distillation at 25-40°C, and then pDO was collected by vacuum distillation at 90-100°C, with a yield of 90%.

[0116] Embodiment 17:

[0117] Under air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 1.33 g of tetramethylammonium acetate (0.01 mol) were added into a reaction bottle and stirred at 180°C for 12 hours. After the reaction was completed, the temperature was restored to room temperature and pDO was collected by reduced pressure distillation at 90-100°C with a yield of 92%.

[0118] Embodiment 18:

[0119] In an air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 0.89 g of tetramethylammonium borohydride (0.01 mol) were added to a reaction bottle and stirred at 180°C for 12 hours. After the reaction was completed, the temperature was restored to room temperature and pDO was collected by reduced pressure distillation at 90-100°C with a yield of 72%.

[0120] Embodiment 19:

[0121] In an air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 2.45 g of tetramethylammonium p-toluenesulfonate (0.01 mol) were added to a reaction flask, stirred at 180°C for 12 hours, and after the reaction, the temperature was restored to room temperature, and pDO was collected by vacuum distillation at 90-100°C, with a yield of 89%. B. Synthesis of pDO by ethylene carbonate catalyzed by an inorganic base / organic base catalyst

[0122] Embodiment 20:

[0123] Under air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 0.35 g of ammonium hydroxide (0.01 mol) were added into a reaction bottle and stirred at 180°C for 12 hours. After the reaction was completed, the temperature was restored to room temperature and pDO was collected by reduced pressure distillation at 90-100°C with a yield of 86%.

[0124] Embodiment 21:

[0125] Under air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 0.35 g of tetramethylammonium hydroxide (0.01 mol) were added into a reaction bottle and stirred at 180°C for 12 hours. After the reaction was completed, the temperature was restored to room temperature and pDO was collected by reduced pressure distillation at 90-100°C with a yield of 89%.

[0126] Embodiment 22:

[0127] Under air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 2.03 g of tetrapropylammonium hydroxide (0.01 mol) were added into the reaction bottle and stirred at 180°C for 12 hours. After the reaction was completed, the temperature was restored to room temperature and pDO was collected by reduced pressure distillation at 90-100°C with a yield of 89%.

[0128] Embodiment 23:

[0129] Under air atmosphere, add 76g glycolic acid (1.0mol), 88g ethylene carbonate (1.0mol) and 0.4g sodium hydroxide (0.01mol) into the reaction bottle, stir at 100°C for 6 hours, return to room temperature after the reaction, wash with deionized water to remove sodium hydroxide, and collect pDO by reduced pressure distillation at 90-100°C, with a yield of 32%.

[0130] Embodiment 24:

[0131] In an air atmosphere, add 76g glycolic acid (1.0mol), 88g ethylene carbonate (1.0mol) and 4g sodium hydroxide (0.1mol) into a reaction bottle, stir at 150°C for 6 hours, return to room temperature after the reaction, wash with deionized water to remove sodium hydroxide, and collect pDO by vacuum distillation at 90-100°C, with a yield of 61%.

[0132] Embodiment 25:

[0133] In an air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 0.4 g of sodium hydroxide (0.1 mol) were added to a reaction flask, stirred at 150°C for 6 hours, and after the reaction, the mixture was returned to room temperature and washed with deionized water to remove the sodium hydroxide. pDO was collected by vacuum distillation at 90-100°C, with a yield of 81%.

[0134] Embodiment 26:

[0135] In an air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 1.38 g of potassium carbonate (0.1 mol) were added to a reaction flask, stirred at 150°C for 6 hours, and after the reaction, the mixture was returned to room temperature and washed with deionized water to remove potassium carbonate. pDO was collected by vacuum distillation at 90-100°C, with a yield of 44%.

[0136] Embodiment 27:

[0137] In an air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 1.39 g of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) (0.1 mol) were added to a reaction flask, stirred at 150°C for 6 hours, and returned to room temperature after the reaction was completed. pDO was collected by reduced pressure distillation at 90-100°C, with a yield of 80%.

[0138] Embodiment 28:

[0139] In an air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 1.52 g of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) (0.1 mol) were added to a reaction flask, stirred at 150°C for 6 hours, and returned to room temperature after the reaction was completed. pDO was collected by vacuum distillation at 90-100°C, with a yield of 87%.

[0140] Embodiment 29:

[0141] Under air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 1.01 g of triethylamine (0.1 mol) were added into a reaction bottle and stirred at 180°C for 12 hours. After the reaction was completed, the temperature was restored to room temperature and pDO was collected by reduced pressure distillation at 90-100°C with a yield of 47%.

[0142] Embodiment 30:

[0143] In an air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 5.05 g of triethylamine (0.5 mol) were added to a reaction bottle and stirred at 100°C for 12 hours. After the reaction was completed, the temperature was restored to room temperature. The triethylamine was first removed by reduced pressure distillation at 25°C, and then pDO was collected by reduced pressure distillation at 90-100°C. The yield was 77%.

[0144] Embodiment 31:

[0145] In an air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 10.1 g of triethylamine (1.0 mol) were added to a reaction bottle and stirred at 100°C for 12 hours. After the reaction was completed, the temperature was restored to room temperature. The triethylamine was first removed by reduced pressure distillation at 25°C, and then pDO was collected by reduced pressure distillation at 90-100°C. The yield was 90%.

[0146] C. Synthesis of pDO from glycolic acid derivatives and ethylene carbonate catalyzed by quaternary ammonium salt-base composite catalyst

[0147] Embodiment 32:

[0148] In an air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol), 2.78 g of tetrabutylammonium chloride (0.01 mol) and 5.05 g of triethylamine (0.5 mol) were added into a reaction bottle and stirred at 140°C for 6 hours. After the reaction was completed, the temperature was restored to room temperature. The triethylamine was first removed by vacuum distillation at 25°C, and then pDO was collected by vacuum distillation at 90-100°C. The yield was 97%.

[0149] Embodiment 33:

[0150] In an air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol), 3.22 g of tetrabutylammonium bromide (0.01 mol) and 5.05 g of triethylamine (0.5 mol) were added into a reaction bottle and stirred at 140°C for 6 hours. After the reaction was completed, the temperature was restored to room temperature. The triethylamine was first removed by vacuum distillation at 25°C, and then pDO was collected by vacuum distillation at 90-100°C. The yield was 95%.

[0151] D. Synthesis of pDO by catalysis of glycolic acid derivatives and ethylene carbonate with organic / inorganic acid catalysts

[0152] Embodiment 34:

[0153] Under air atmosphere, add 90g methyl glycolate (1.0mol), 88g ethylene carbonate (1.0mol) and 1.1mL concentrated sulfuric acid (0.01mol) into the reaction bottle, stir at 180℃ for 12 hours, return to room temperature after the reaction is completed, and then collect pDO by reduced pressure distillation at 90-100℃, with a yield of 45%.

[0154] Embodiment 35:

[0155] Under air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 1.50 g of trifluoromethanesulfonic acid (0.01 mol) were added into a reaction bottle and stirred at 180°C for 12 hours. After the reaction was completed, the temperature was restored to room temperature, and then pDO was collected by reduced pressure distillation at 90-100°C with a yield of 56%.

[0156] E. Synthesis of pDO by Polyquaternium Salt Catalyzed by Glycolate and Ethylene Carbonate

[0157] Embodiment 36:

[0158] Under air atmosphere, add 90g methyl glycolate (1.0mol), 88g ethylene carbonate (1.0mol) and 1.26g dimethyldiallylammonium chloride homopolymer (polyquaternium-6) (quaternary ammonium salt is 0.01mol) into a reaction bottle, stir at 180°C for 12 hours, return to room temperature after the reaction is completed, recover polyquaternium-6 by filtration or rotary centrifugation, and then collect pDO by reduced pressure distillation at 90-100°C, with a yield of 90%.

[0159] Embodiment 37:

[0160] In an air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 10 g of 2-hydroxy-3-(trimethylamino)propyl polyoxyethylene cellulose ether (polyquaternium-10) were added to a reaction bottle and stirred at 180° C. for 12 hours. After the reaction was completed, the temperature was restored to room temperature. Polyquaternium-10 was recovered by filtration or rotary centrifugation, and then pDO was collected by reduced pressure distillation at 90-100° C. with a yield of 56%.

[0161] F. Synthesis of pDO from glycolate and ethylene carbonate catalyzed by quaternary phosphonium salts

[0162] Embodiment 38:

[0163] Under air atmosphere, 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 3.74 g of tetraphenylphosphonium chloride (0.01 mol) were added into a reaction bottle and stirred at 180°C for 12 hours. After the reaction was completed, the temperature was restored to room temperature, and then pDO was collected by reduced pressure distillation at 90-100°C with a yield of 86%.

[0164] G. Synthesis of pDO from glycolate and ethylene carbonate catalyzed by solid catalyst

[0165] Embodiment 39:

[0166] In an air atmosphere, add 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 10 g of acidic molecular sieve ZSM-5 into a reaction bottle and stir at 180°C for 12 hours. After the reaction is completed, return the temperature to room temperature, recover the molecular sieve by filtration or rotary centrifugation, and then collect pDO by reduced pressure distillation at 90-100°C, with a yield of 36%.

[0167] Embodiment 40:

[0168] In an air atmosphere, add 90 g of methyl glycolate (1.0 mol), 88 g of ethylene carbonate (1.0 mol) and 10 g of weakly basic anion exchange resin D301 into a reaction bottle and stir at 180°C for 12 hours. After the reaction is completed, return the temperature to room temperature, recover the D301 resin by filtration or rotary centrifugation, and then collect pDO by reduced pressure distillation at 90-100°C, with a yield of 77%.

[0169] H. Design and Implementation of Fixed Bed Reactors

[0170] Embodiment 41:

[0171] First, polyquaternium salt-6 and 200-300 mesh silica gel particles are mixed evenly to prepare a solid catalyst, and then the catalyst is loaded into a stainless steel reaction tube with an inner diameter of 5 mm and a length of 3 meters (three 1-meter tubes connected in series), and the catalyst is compacted in the reaction tube using an apparatus and high-pressure air ventilation pressure. After the catalyst is loaded, the inlet section is connected to a peristaltic pump, and then a receiving bottle is placed at the outlet section, and finally the reaction tube is placed in a column oven.

[0172] Methyl glycolate and carbonate are mixed in a tank at a molar ratio of 1:1, and then the peristaltic pump flow rate is set to 0.1-0.2 mL / min, and the column oven temperature is set to 180°C. After stabilization, the pump switch is turned on, and the mixed raw materials enter the reaction tube to start the reaction, and at the same time, observe whether the reaction pressure exceeds the upper limit of the pressure. Adjust the receiving product at the outlet, collect a certain amount of the product, and recover the unreacted methyl glycolate and carbonate by vacuum distillation at 30-70°C, and then add it back to the raw material tank, and collect pDO by vacuum distillation at 90-100°C. pDO is purified by two distillations to finally obtain high-purity pDO.

[0173] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing 1,4-dioxane-2-one from ethylene carbonate, characterized in that: The method comprises: mixing a glycolic acid derivative, ethylene carbonate and a catalyst, and reacting to obtain the 1,4-dioxane-2-one; wherein the glycolic acid derivative has the following structural formula: In the formula, R is hydrogen, a C1-C8 alkyl group with a substituent, a C3-C8 cycloalkyl group with a substituent, an aromatic group with a substituent, or an aromatic heterocyclic group with a substituent; the substituent is a halogen, a C1-C3 alkyl group, a halogenated C1-C3 alkyl group, a C1-C3 alkoxy group, a hydroxyl group, a nitro group, or an amino group; and the heteroatom in the aromatic heterocyclic group is nitrogen, sulfur, or oxygen.

2. The method according to claim 1, characterized in that The glycolic acid derivative is glycolic acid, methyl glycolate, ethyl glycolate, n-propyl glycolate, isopropyl glycolate, n-butyl glycolate, isobutyl glycolate, tert-butyl glycolate, phenyl glycolate or benzyl glycolate.

3. The method according to claim 1, characterized in that The catalyst is selected from one or more of ammonium salt catalysts, quaternary ammonium salt catalysts, polyquaternary ammonium salt catalysts, quaternary phosphonium salt catalysts, inorganic acid catalysts, organic acid catalysts, inorganic base catalysts, organic base catalysts, Lewis acid-base pair catalysts, ionic liquid catalysts, solid alkaline catalysts, solid acid catalysts, and metal salt catalysts.

4. The method according to claim 3, characterized in that: The structural formula of the quaternary ammonium salt catalyst is as follows: R is a C1-C 22 Alkyl, aromatic group with a substituent or aromatic heterocyclic group with a substituent; the substituent is C1-C 10 Alkyl, C1-C 10 Alkoxy or hydroxyl, the heteroatom in the aromatic heterocyclic group is nitrogen, sulfur or oxygen; X is fluoride, chloride, bromide, iodide, carboxylate, sulfate, sulfite, bisulfate, nitrate, nitrite, carbonate, bicarbonate, chlorate, phosphate, borate, silicate or sulfonate; The ammonium salt catalyst is selected from one or more of ammonium fluoride, ammonium chloride, ammonium bromide and ammonium iodide; The quaternary phosphonium salt is selected from one or more of methyltriphenylphosphonium chloride, benzyltriphenylphosphonium chloride, tetraphenylphosphonium chloride, trihexyltetradecylphosphonium chloride, tetrabutylphosphonium chloride, methoxymethyltriphenylphosphonium chloride, methyltriphenylphosphonium bromide, benzyltriphenylphosphonium bromide, tetraphenylphosphonium bromide, trihexyltetradecylphosphonium bromide, tetrabutylphosphonium bromide and methoxymethyltriphenylphosphonium bromide; The polyquaternium salt is selected from one or more of polyquaternium-6, polyquaternium-10, and polyquaternium-55; The inorganic acid catalyst is selected from one or more of sulfuric acid, hydrochloric acid, hydrobromic acid, tungstic acid, titanic acid, and boric acid; The organic acid catalyst is selected from one or more of methanesulfonic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid, boron trifluoride, boron trifluoride ethyl ether, tri(pentafluorophenyl)boron, triethylboron, camphorsulfonic acid, benzoic acid, salicylic acid, oxalic acid, and malic acid; The inorganic base catalyst is selected from one or more of sodium hydride, lithium hydride, calcium hydride, sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, lithium hydroxide, magnesium hydroxide, zinc hydroxide, copper hydroxide, iron hydroxide, and ammonium hydroxide; The organic base catalyst is selected from one or more of triethylamine, pyridine, 4-dimethylaminopyridine, 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, and hexamethyldisilazane; The metal salt catalyst is selected from one or more of copper tetrafluoroborate, bismuth trifluoride, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, calcium carbonate, cesium carbonate, sodium glycolate, sodium acetate, lithium diisopropylamide, sodium methoxide, sodium ethoxide, sodium tert-butoxide, potassium tert-butoxide, n-butyl lithium, and isobutyl lithium; The ionic liquid catalyst is selected from one or more of imidazole ionic liquids, pyridine ionic liquids, quaternary ammonium salt ionic liquids, and quaternary phosphonium salt ionic liquids; The solid acid catalyst is selected from one or more of supported acid catalysts, acidic molecular sieves, cation exchange resins, natural clays, metal sulfur or oxides, and acidic catalyst complexes; The solid base catalyst is selected from one or more of supported base catalysts, acidic molecular sieves, anion exchange resins, alkali metal sulfur or oxides, and alkaline catalyst complexes.

5. The method according to claim 1, characterized in that: The molar ratio of the catalyst to the ethylene carbonate is 1:50 to 1:1000.

6. The method according to claim 1, characterized in that: The molar ratio of the glycolic acid derivative to the ethylene carbonate is 10:1 to 1:

10.

7. The method according to claim 1, characterized in that: Before stirring and mixing, the step of adding an organic solvent to the reaction system is also included: wherein the organic solvent is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, tetrahydrofuran, dioxane, dichloroethane, chloroform, carbon tetrachloride, toluene, xylene, and trimethylbenzene.

8. The method according to claim 1, characterized in that: The reaction temperature is 0-200°C, and the reaction time is 1-24h.

9. The method according to claim 1, characterized in that: After the reaction is completed, the method further comprises the steps of separating and purifying the obtained crude product.

10. A 1,4-dioxane-2-one, characterized in that: The preparation method is described in any one of claims 1 to 9.

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